This invention relates to wind turbines.
1. Prior Art
In U.S. Pat. No. 6,616,402 I introduce a downwind-projecting, co-axial, multi-rotor, wind turbine that orients the driveshaft at an offset angle from the wind direction, allowing fresh wind to each rotor. The advantages include lighter total rotor weight for the swept area, and higher rpm for a given power rating. Shaft rotation at higher rpm delivers a given amount of power at less torque, and requires a smaller generator, and/or less gearing for the same power output.
In U.S. Pat. No. 6,692,230 I introduce a balanced version of the co-axial, multi-rotor wind turbine, having an upwind section of the driveshaft that serves to some degree as a counterbalance to the downwind section of the driveshaft. This upwind section, like the downwind section, has rotors attached at spaced intervals, adding power to the system. In the second embodiment of this U.S. Pat. No. 6,692,230 illustrated in FIGS. 9 and 10 of that patent, a counterweight attached to the upwind section of the driveshaft serves to counterbalance against a much longer downwind section of the driveshaft. The extra length of the downwind section allows the attachment of additional rotors, providing even more power.